نتایج جستجو برای: acoustic wave propagation

تعداد نتایج: 376367  

2008
Li Sun Yong Yu Gangbing Song Jihua Gou

Polymer composites reinforced by carbon nanofibers CNFs in the form of paper sheet show significant vibration and acoustic damping improvement when compared to pure matrix materials. Without looking into the microscopic energy dissipation mechanisms, this paper analyzes the wave propagation in the composites from a macroscopic point of view. The CNF nanocomposites in this study were treated as ...

2017
Giovanni Giuliano Lionel W. J. Kent Leslie C. Laycock

The present study originated in the lack of research into achieving underwater total internal reflection (TIR) via the acousto-optic effect. The uniqueness of this technique exists in the fact that it is based on a high sound pressure level which induces a localised change in refractive index of seawater sufficient to achieve total internal reflection within the communication channel. Different...

Journal: :The international journal of multiphysics 2011
Kenneth Hoyt

Acoustic radiation forces associated with high intensity focused ultrasound stimulate shear wave propagation allowing shear wave speed and shear viscosity estimation of tissue structures. As wave speeds are meters per second, real time displacement tracking over an extend field-of-view using ultrasound is problematic due to very high frame rate requirements. However, two spatially separated dyn...

2017
R S Crum J P Domann V Gupta

Previous studies examining the response of magnetoelastic materials to shock waves have predominantly focused on applications involving pulsed power generation, with limited attention given to the actual wave propagation characteristics. This study provides detailed magnetic and mechanical measurements of magnetoelastic shock wave propagation and dispersion. Laser generated rarefacted shock wav...

2003
P. N. Gélat

Recent advances in computing power and signal processing techniques have highlighted the need for a greater understanding of acoustic emission (AE) wave propagation and the interactions with the sensor being used. Complex structures often lead to numerous wave modes being generated which arrive at a surface mounted sensor from different angles of incidence and in different planes. To fully unde...

Journal: :نشریه دانشکده فنی 0
همایون عریضی نرگس نوری

with the rapid growth of indoor wireless communication systems, the need to accurately model radio wave propagation inside the building environments has increased. many site-specific methods have been proposed for modeling indoor radio channels. among these methods, the ray tracing algorithm and the finite-difference time domain (fdtd) method are the most popular ones. the ray tracing approach ...

2010
Kunitoshi Motoki

This paper presents the effects of a wall impedance on the propagation of higher-order modes in a three-dimensional vocal-tract model. This model is constructed using an asymmetrically connected structure of rectangular acoustic tubes, and can parametrically represent acoustic characteristics in higher frequencies where the assumption of the plane wave propagation does not hold. The propagation...

Journal: :The Journal of the Acoustical Society of America 2009
Jorge E Quijano Lisa M Zurk

Research on the propagation of acoustic waves in the ocean bottom sediment is of interest for active sonar applications such as target detection and remote sensing. The interaction of acoustic energy with the sea floor sublayers is usually modeled with techniques based on the full solution of the wave equation, which sometimes leads to mathematically intractable problems. An alternative way to ...

2003
N. C. R. Holme B. C. Daly M. T. Myaing T. B. Norris

Ultrafast laser pulses are used to generate single-cycle picosecond acoustic pulses in thin metal films on silicon. For small initial excitation spot sizes, propagation of the acoustic pulses across a 485-mm Si crystal leads to significant diffraction effects. The temporal reshaping of the acoustic wave form due to diffraction is investigated, and we demonstrate that the acoustic far field can ...

2009
O. Richoux L. Simon

This paper presents an analytical approach of the propagation of an acoustic wave through a normally distributed disordered lattice made up of Helmholtz resonators connected to a cylindrical duct. This approach allows to determine analytically the exact transmission coefficient of a weakly disordered lattice. Analytical results are compared to a well-known numerical method based on a matrix pro...

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